Hi,
Thanks for the quick reply. It seems that it was a codec issue (H.264). I resaved the file in quicktime as an MP4 file and that seemed to sort it.
However, seeing as we’re on the subject of sound, I have some footage which features somebody talking but also has some subtle background music. Is there a way I may be able to reduce the bg soundtrack but keep the talking, or is this something that after effects cannot handle???